Differences in Femoral Neck and Trochanteric Structure in Elderly Women Prior to Hip Fracture: Role in Hip Fracture Prediction.

We examine the hypothesis that internal dual-energy X-ray absorptiometry (DXA) structural variables measured at the femoral neck and trochanter cross sections will improve prediction of fractures at these sites in addition to areal BMD (aBMD). We present an analysis of the internal distribution of bone at the site of these fractures using baseline hip DXA measurement of 1151 participants, mean age (SD) 75 (3) years, in the 14.5-year Perth Longitudinal Study of Aging in Women. Structural differences at the femoral neck (FN) and trochanter (TR) cross sections were compared in 69 participants who went on to sustain femoral neck fracture (FNF) and 59 participants who went on to sustain trochanter fracture (TRF), on average 10 years later, to those who did not fracture. The new structural variables, in addition to aBMD and bone width (W), were Sigma (distribution of bone within scanned area) and Delta (distance between center-of-mineral mass and geometric center), which can be assessed by current DXA programs. At baseline, compared with nonfracture cases, FNF cases had a FNaBMD 7% lower, a FNWidth 3% higher and a FNDelta 29% higher, associated with reduced bone in the superior segment. In FNF Cox proportional hazard analysis, age (hazard ratio [HR 1.39]), total hip aBMD (THaBMD; 0.79), and Delta (1.70) were significant. Addition of FN Delta to the base case of THaBMD and age improved the C statistic from 0.62 to 0.69, p = 0.01. At baseline, TRF cases had a 15% lower TRaBMD with minor differences in Sigma (1%) and Width (2%). In TRF Cox analysis, neither addition of Sigma nor Width improved the model that included age and THaBMD as predictors and did not alter the C-statistic of 0.81. In conclusion, adding measurement of FN Delta, an assessment of superior sector bone loss, to hip aBMD and age substantially improved clinical FNF prediction in older women. © 2023 American Society for Bone and Mineral Research (ASBMR).

Structural Factors Associated With Femoral Neck Fractures and its Prediction in Chinese Males.

We have recently proposed a new approach to evaluate 2D femoral neck (FN) structure, named the Minimal Model (MM), that comprised FN areal bone mineral density (FNaBMD) and FNWidth and 2 new internal structural measures; (1) the standard deviation of normalized mineral mass projection profile distribution (FNSigma), and (2) the displacement between center-of-mineral mass and geometric center of mineral mass projection profile (FNDelta). The contralateral hip of 67 FN fracture Chinese male patients had a QCT scan shortly after fracture and was compared to 156 community participants without hip fracture. The QCT scans were analyzed using Mindways software to enable DXA-equivalent 2D images to be obtained; MM variables were calculated from these images. In FN fracture and nonfracture participants, the 4 MM variables as well as age, weight and height were compared. Compared to nonfracture, fracture participants were older, weighed less and were taller. After adjustment for these differences FN fracture participants compared to nonfracture had mean ± SD lower FNaBMD 0.54 ± 0.11 vs 0.70 ± 0.11 g/cm2 (p < 0.001); larger FNSigma 1.05 ± 0.11 vs 0.98 ± 0.10 cm (p < 0.001); larger FNDelta 0.43 ± 0.09 vs 0.33 ± 0.09 cm (p < 0.001), however FNWidth did not differ 2.96 ± 0.35 vs 2.92 ± 0.34 cm. All variables except FNaBMD and FNWidth were correlated; however logistic regression identified increased age and height, reduced FNaBMD and increased FNSigma as independent contributors to differentiating participants with FN fracture from nonfracture. Area under ROC analysis identified significant improvement in discrimination with addition of FNSigma to the base model of Age and FNaBMD (C statistic 0.88 and 0.91, p = 0.019). These analyses identified important internal structural information available from 2D DXA imaging that contributes to discrimination of FN fracture in addition to low bone mass. This analytical approach may contribute to improved clinical FN fracture prediction, extending value of widely available DXA technology.

Quantitative CT Detects Undiagnosed Low Bone Mineral Density in Oncologic Patients Imaged With 18F-FDG PET/CT.

PURPOSE: We assessed the prevalence of low bone mineral density (BMD) in oncologic patients undergoing F-FDG PET/CT. PATIENTS AND METHODS: This is a retrospective analysis of 100 patients who underwent F-FDG PET/CT at a single center from October 2015 till May 2016. Quantitative CT (QCT) was used to assess BMD at the lumbar spine (BMDQCT) and femoral necks (BMDCTXA). SUVmax was used to evaluate metabolic activity of the bone marrow. Risk of osteoporosis-related fractures was calculated with femoral neck BMDCTXA and the FRAX algorithm, which was compared against measurements of CT attenuation of the trabecular bone at L1 (L1HU). RESULTS: Osteoporosis and osteopenia were respectively present in 16% and 46% of patients 50 years and older. Bone marrow SUVmax was correlated with BMD at the lumbar spine (ρ = 0.36, P < 0.001). Increased age and low marrow SUVmax were associated with low BMDQCT at the lumbar spine (both P < 0.001), whereas increased age, female sex, and low marrow SUVmax were associated with low BMDCTXA at the femoral necks (P < 0.001, P < 0.001, P = 0.01, respectively). L1HU had an area under the curve of 0.95 (95% confidence interval [CI], 0.90-0.99) for detecting increased risk for osteoporosis-related fracture, with best threshold of 125.8 HU (95% CI, 115.7-144.9) yielding sensitivity of 100% (95% CI, 0.92-1.00), specificity of 0.90 (95% CI, 0.76-0.97), and accuracy of 0.91 (95% CI, 0.79-0.97). CONCLUSIONS: Low BMD is frequent in oncologic patients undergoing F-FDG PET/CT. Decreased F-FDG avidity of the bone marrow correlates with decreased BMD, validating the link between osteoporosis and bone marrow fat. L1HU could be a simple and accurate approach for detecting patients at risk for osteoporosis-related fractures using PET/CTdata.

Anatomical factors associated with femoral neck fractures of elderly Beijing women.

Analyses using newly developed structural measures of minimal model (aBMD, W, Sigma, Delta) in a Chinese female age-matched cohort of femoral neck fracture patients and non-fracture community controls resulted in improved fracture prediction, suggesting the usefulness of new variables, extending the value of widely available DXA technology. INTRODUCTION: We have developed a new approach to evaluate 2D femoral neck (FN) structure, the minimal model (MM). This model includes FNaBMD and FNWidth with two new internal structural measures, the standard deviation of normalized mineral mass projection profile distribution (FNSigma) and the displacement between center of mineral (CoM) mass and geometric center of mineral mass projection profile (FNDelta). METHODS: Differences in these four structural measurements together with age, weight, and height were compared in the contralateral hip of 285 FN fracture Chinese female patients and 261 age-matched community controls. Structural variables were calculated from DXA equivalent 2D images obtained from QCT scans analyzed using Mindways Software. RESULTS: Review of FN scanned profiles of fracture patients and controls identified substantial reduction in mineral mass in the superior segment of FN. Fracture participants were taller, weighed less, and had lower FNaBMD and larger FNDelta, due to a larger inferior displacement in the CoM, consistent with greater reduction in superior segment bone. Logistic regression identified increased height, reduced FNaBMD, increased FNDelta, and reduced FNSigma per SD as significant independent contributors to differentiating fracture from non-fracture. Area under ROC analysis identified significant improvement in discrimination with the addition of FNDelta and FNSigma to the model including age, height, weight, and FNaBMD (C statistic 0.87 and 0.84 respectively). CONCLUSIONS: These data extend previous data that identified the benefit of 2D FN internal structural information in discriminating those at increased future fracture risk from recently fractured individuals. These data support continuing investigation of MM analysis as a straightforward analytical approach adding value to DXA hip aBMD in predicting fracture risk.

Implant migration and bone mineral density measured simultaneously by low-dose CT scans: a 2-year study on 17 acetabular revisions with impaction bone grafting.

Background and purpose - Early postoperative implant migration predicts failure of joint replacements. Bone mineral density reflects bone quality and bone-graft incorporation. Implant migration and bone densitometry analysis usually require special equipment. We investigated cup migration and bone mineral density changes simultaneously with low-dose CT scans after acetabular revision hip arthroplasty using impaction bone grafting.Patients and methods - We performed a low-dose CT postoperatively, after 6 weeks, and after 2 years in 17 patients, all revised using impaction bone grafting and a graft-compressing titanium shell in the acetabulum. 6 patients had combined segmental and cavitary acetabular defects. Cup migration was analyzed using CT-based micromotion analysis (CTMA). Bone mineral density was determined in the graft and in surrounding native bone using volumetric quantitative computed tomography (QCT). The bone graft volume was calculated from 3D reconstructions.Results - At 2 years, the translations were 1.5 (95% CI 0.4-2.6) mm in proximal direction, -0.6 (CI -1.6 to 0.4) in the medial direction and 0.3 (CI 0.0-0.6) in the anterior direction. The mean volume of impacted bone graft was 40 cm³ (CI 28-52). In the graft bone mineral density increased 14% after 6 weeks and 23% after 2 years. There was 1 mechanical failure.Interpretation - Proximal migration of the acetabular component was low and comparable to previous reports. There was a rapid increase of bone mineral density in the bone graft. Low-dose CT scans make migration analysis and bone densitometry measurements possible in the same setting, offering great diagnostic potential for hip arthroplasty patients.

QCT of the femur: Comparison between QCTPro CTXA and MIAF Femur.

QCT is commonly employed in research studies and clinical trials to measure BMD at the proximal femur. In this study we compared two analysis software options, QCTPro CTXA and MIAF-Femur, using CT scans of the semi-anthropometric European Proximal Femur Phantom (EPFP) and in vivo data from 130 Chinese elderly men and women aged 60-80 years. Integral (Int), cortical (Cort) and trabecular (Trab) vBMD, volume, and BMC of the neck (FN), trochanter (TR), inter-trochanter (IT), and total hip (TH) VOIs were compared. Accuracy was determined in the 5 mm wide central portion of the femoral neck of the EPFP. Nominal values were: cross-sectional area (CSA) 4.9 cm2, cortical thickness (C.Th) 2 mm, CortBMD 723 mg/cm3 and TrabBMD 100 mg/cm3. In MIAF the so-called peeled trabecular VOI was analyzed, which excludes subcortical bone to avoid partial volume artefacts at the endocortical border that artificially increase TrabBMD. For CTXA uncorrected, so called raw cortical values were used for the analysis. QCTPro and MIAF phantom results were: CSA 5.9 cm2 versus 5.1 cm2; C.Th 1.68 mm versus 1.92 mm; CortBMD 578 mg/cm3 versus 569 mg/cm3; and TrabBMD 154 mg/cm3 versus 104 mg/cm3. In vivo correlations (R2) of integral and trabecular bone parameters ranged from 0.63 to 0.96. Bland-Altman analysis for TH and FN TrabBMD showed that lower mean values were associated with higher differences, which means that TrabBMD differences between MIAF and CTXA are larger for osteoporotic than for normal patients, which can be largely explained by the inclusion of subcortical BMD in the trabecular VOI analyzed by CTXA in combination with fixed thresholds used to separate cortical from trabecular bone compartments. Correlations between CTXA corrected CortBMD and MIAF were negative, whereas raw data correlated positively with MIAF measurements for all VOIs questioning the validity of the CTXA corrections. The EPFP results demonstrated higher MIAF accuracy of cortical thickness and TrabBMD. Integral and trabecular bone parameters were highly correlated between CTXA and MIAF. Partial volume artefacts at the endocortical border artificially increased trabecular BMD by CTXA, especially for osteoporosis patients. With respect to volumetric cortical measurements with CTXA, the use raw data is recommended, because corrected data cause a negative correlation with MIAF CortBMD.

Validation of goose liver fat measurement by QCT and CSE-MRI with biochemical extraction and pathology as reference.

OBJECTIVES: This study aimed to validate the accuracy and reliability of quantitative computed tomography (QCT) and chemical shift encoded magnetic resonance imaging (CSE-MRI) to assess hepatic steatosis. METHODS: Twenty-two geese with a wide range of hepatic steatosis were collected. After QCT and CSE-MRI examinations, the liver of each goose was removed and samples were taken from the left lobe, upper and lower half of the right lobe for biochemical measurement and histology. Fat percentages by QCT and proton density fat fraction by MRI (MRI-PDFF) were measured within the sample regions of biochemical measurement and histology. The accuracy of QCT and MR measurements were assessed through Spearman correlation coefficients (r) and Passing and Bablok regression equations using biochemical measurement as the "gold standard". RESULTS: Both QCT and MRI correlated highly with chemical extraction [r = 0.922 (p < 0.001) and r = 0.949 (p < 0.001) respectively]. Chemically extracted triglyceride was accurately predicted by both QCT liver fat percentages (Y = 0.6 + 0.866 × X) and by MRI-PDFF (Y = -1.8 + 0.773 × X). CONCLUSIONS: QCT and CSE-MRI measurements of goose liver fat were accurate and reliable compared with biochemical measurement. KEY POINTS: • QCT and CSE-MRI can measure liver fat content accurately and reliably • Histological grading of hepatic steatosis has larger sampling variability • QCT and CSE-MRI have potential in the clinical setting.

Whole-Body Distribution of Leukemia and Functional Total Marrow Irradiation Based on FLT-PET and Dual-Energy CT.

This report describes a multimodal whole-body 3'-deoxy-3'[(18)F]-fluorothymidine positron emission tomography (FLT-PET) and dual-energy computed tomography (DECT) method to identify leukemia distribution within the bone marrow environment (BME) and to develop disease- and/or BME-specific radiation strategies. A control participant and a newly diagnosed patient with acute myeloid leukemia prior to induction chemotherapy were scanned with FLT-PET and DECT. The red marrow (RM) and yellow marrow (YM) of the BME were segmented from DECT using a basis material decomposition method. Functional total marrow irradiation (fTMI) treatment planning simulations were performed combining FLT-PET and DECT imaging to differentially target irradiation to the leukemia niche and the rest of the skeleton. Leukemia colonized both RM and YM regions, adheres to the cortical bone in the spine, and has enhanced activity in the proximal/distal femur, suggesting a potential association of leukemia with the BME. The planning target volume was reduced significantly in fTMI compared with conventional TMI. The dose to active disease (standardized uptake value >4) was increased by 2-fold, while maintaining doses to critical organs similar to those in conventional TMI. In conclusion, a hybrid system of functional-anatomical-physiological imaging can identify the spatial distribution of leukemia and will be useful to both help understand the leukemia niche and develop targeted radiation strategies.

Evaluation of Functional Marrow Irradiation Based on Skeletal Marrow Composition Obtained Using Dual-Energy Computed Tomography.

PURPOSE: To develop an imaging method to characterize and map marrow composition in the entire skeletal system, and to simulate differential targeted marrow irradiation based on marrow composition. METHODS AND MATERIALS: Whole-body dual energy computed tomography (DECT) images of cadavers and leukemia patients were acquired, segmented to separate bone marrow components, namely, bone, red marrow (RM), and yellow marrow (YM). DECT-derived marrow fat fraction was validated using histology of lumbar vertebrae obtained from cadavers. The fractions of RM (RMF = RM/total marrow) and YMF were calculated in each skeletal region to assess the correlation of marrow composition with sites and ages. Treatment planning was simulated to target irradiation differentially at a higher dose (18 Gy) to either RM or YM and a lower dose (12 Gy) to the rest of the skeleton. RESULTS: A significant correlation between fat fractions obtained from DECT and cadaver histology samples was observed (r=0.861, P<.0001, Pearson). The RMF decreased in the head, neck, and chest was significantly inversely correlated with age but did not show any significant age-related changes in the abdomen and pelvis regions. Conformity of radiation to targets (RM, YM) was significantly dependent on skeletal sites. The radiation exposure was significantly reduced (P<.05, t test) to organs at risk (OARs) in RM and YM irradiation compared with standard total marrow irradiation (TMI). CONCLUSIONS: Whole-body DECT offers a new imaging technique to visualize and measure skeletal-wide marrow composition. The DECT-based treatment planning offers volumetric and site-specific precise radiation dosimetry of RM and YM, which varies with aging. Our proposed method could be used as a functional compartment of TMI for further targeted radiation to specific bone marrow environment, dose escalation, reduction of doses to OARs, or a combination of these factors.

A phase I feasibility study of multi-modality imaging assessing rapid expansion of marrow fat and decreased bone mineral density in cancer patients.

PURPOSE: Cancer survivors are at an increased risk for fractures, but lack of effective and economical biomarkers limits quantitative assessments of marrow fat (MF), bone mineral density (BMD) and their relation in response to cytotoxic cancer treatment. We report dual energy CT (DECT) imaging, commonly used for cancer diagnosis, treatment and surveillance, as a novel biomarker of MF and BMD. METHODS: We validated DECT in pre-clinical and phase I clinical trials and verified with water-fat MRI (WF-MRI), quantitative CT (QCT) and dual-energy X-ray absorptiometry (DXA). Basis material composition framework was validated using water and small-chain alcohols simulating different components of bone marrow. Histologic validation was achieved by measuring percent adipocyte in the cadaver vertebrae and compared with DECT and WF-MRI. For a phase I trial, sixteen patients with gynecologic malignancies (treated with oophorectomy, radiotherapy or chemotherapy) underwent DECT, QCT, WF-MRI and DXA before and 12months after treatment. BMD and MF percent and distribution were quantified in the lumbar vertebrae and the right femoral neck. RESULTS: Measured precision (3mg/cm(3)) was sufficient to distinguish test solutions. Adiposity in cadaver bone histology was highly correlated with MF measured using DECT and WF-MRI (r=0.80 and 0.77, respectively). In the clinical trial, DECT showed high overall correlation (r=0.77, 95% CI: 0.69, 0.83) with WF-MRI. MF increased significantly after treatment (p<0.002). Chemotherapy and radiation caused greater increases in MF than oophorectomy (p<0.032). L4 BMD decreased 14% by DECT, 20% by QCT, but only 5% by DXA (p<0.002 for all). At baseline, we observed a statistically significant inverse association between MF and BMD which was dramatically attenuated after treatment. CONCLUSION: Our study demonstrated that DECT, similar to WF-MRI, can accurately measure marrow adiposity. Both imaging modalities show rapid increase in MF following cancer treatment. Our results suggest that MF and BMD cannot be used interchangeably to monitor skeletal health following cancer therapy.

Effects of the assessment of 4 determinants of structural geometry on QCT- and DXA-derived hip structural analysis measurements in elderly women.

Previously we reported that the corresponding 2-dimensional (2D) structural geometry measures derived from quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) of femoral neck were different. Now, we test the hypothesis that the following 4 measures: areal bone mineral density, W, and 2 new measures, standard deviation (σ) of a normalized mineral mass projection profile distribution and the displacement between centre of mineral mass and geometric centre of mineral mass (δ) of the projection profile allow transformation from one measurement modality to the other with high precision. QCT and DXA scans and hip structural analysis (HSA) performed on 237 women were randomly allocated into cohorts of 118 (cohort A) and 119 (cohort B). Intercepts and gradients from linear regression of the 4 QCT- and DXA-derived measures were obtained from cohort A and used to convert cohort B QCT-derived structural geometry measurements into their DXA equivalent. Corresponding cohort B QCT- and DXA-derived structural geometrical measurements were compared using Bland-Altman plots and regression analysis. Apart from W, comparisons of the 7 nontransformed QCT- and DXA-derived variables were significantly different using paired t-tests. Cross-calibration with the set of 4 base measures resolved the differences in all original variables. These data provide a mechanism for cross-calibrating HSA outcomes acquired using QCT and DXA and demonstrate that a complex 2D digitized structure can be described by 4 variables.

Effect of odanacatib on bone turnover markers, bone density and geometry of the spine and hip of ovariectomized monkeys: a head-to-head comparison with alendronate.

Odanacatib (ODN) is a selective and reversible Cathepsin K (CatK) inhibitor currently being developed as a once weekly treatment for osteoporosis. Here, effects of ODN compared to alendronate (ALN) on bone turnover, DXA-based areal bone mineral density (aBMD), QCT-based volumetric BMD (vBMD) and geometric parameters were studied in ovariectomized (OVX) rhesus monkeys. Treatment was initiated 10 days after ovariectomy and continued for 20 months. The study consisted of four groups: L-ODN (2 mg/kg, daily p.o.), H-ODN (8/4 mg/kg daily p.o.), ALN (15 µg/kg, twice weekly, s.c.), and VEH (vehicle, daily, p.o.). L-ODN and ALN doses were selected to approximate the clinical exposures of the ODN 50-mg and ALN 70-mg once-weekly, respectively. L-ODN and ALN effectively reduced bone resorption markers uNTx and sCTx compared to VEH. There was no additional efficacy with these markers achieved with H-ODN. Conversely, ODN displayed inversely dose-dependent reduction of bone formation markers, sP1NP and sBSAP, and L-ODN reduced formation to a lesser degree than ALN. At month 18 post-OVX, L-ODN showed robust increases in lumbar spine aBMD (11.4%, p<0.001), spine trabecular vBMD (13.7%, p<0.001), femoral neck (FN) integral (int) vBMD (9.0%, p<0.001) and sub-trochanteric proximal femur (SubTrPF) int vBMD, (6.4%, p<0.001) compared to baseline. L-ODN significantly increased FN cortical thickness (Ct.Th) and cortical bone mineral content (Ct.BMC) by 22.5% (p<0.001) and 21.8% (p<0.001), respectively, and SubTrPF Ct.Th and Ct.BMC by 10.9% (p<0.001) and 11.3% (p<0.001) respectively. Compared to ALN, L-ODN significantly increased FN Ct. BMC by 8.7% (p<0.05), and SubTrPF Ct.Th by 7.6% (p<0.05) and Ct.BMC by 6.2% (p<0.05). H-ODN showed no additional efficacy compared to L-ODN in OVX-monkeys in prevention mode. Taken together, the results from this study have demonstrated that administration of ODN at levels which approximate clinical exposure in OVX-monkeys had comparable efficacy to ALN in DXA-based aBMD and QCT-based vBMD. However, FN cortical mineral content clearly demonstrated superior efficacy of ODN versus ALN in this model of estrogen-deficient non-human primates.

Steroid withdrawal in pediatric kidney transplant allows better growth, lipids and body composition: a randomized controlled trial.

BACKGROUND: Glucocorticoid immunosuppressant therapy in pediatric kidney transplant (Tx) recipients does not allow the improvement of growth after Tx. OBJECTIVE: To determine the effect of early steroid withdrawal (SW) on longitudinal growth, insulin sensitivity (IS), and body composition (BC). METHODS: This was a prospective, randomized, multicenter study in Tx. Insulin-like growth factor (IGF)-I, IGF-binding protein 3 (IGFBP3), IS, and BC (DEXA/pQCT) were determined at baseline and up to 12 months after Tx. RESULTS: A total of 30 patients were examined; 14 patients were assigned to the SW group (7 male, 7 female; 12 in Tanner stage I) and 16 patients were assigned to the steroid control (SC) group (10 male, 6 female;12 in Tanner stage I). Their chronological age was 7.8 ± 4.3 years, height was -2.3 ± 0.99 SD scores (SDS), and body mass index -0.3 ± 1.2 SDS. After 1 year, the SW group showed an increase in height SDS (+1.2 ± 0.22 vs. +0.60 ± 0.13 SDS in the SC group, p < 0.02), lower IGFBP3 (p < 0.05), cholesterol (p < 0.05), and higher high-density lipoprotein cholesterol (p < 0.05). SW patients had lower trunk fat with no differences in IS. Only in prepubertal patients, the SW group had lower glycemia (p < 0.05), very low-density lipoprotein cholesterol (p < 0.01), triglycerides (p < 0.05), triglycerides/glycemia index (TyG; p < 0.02), and better lean mass. Both groups showed an improvement in lean mass after kidney Tx. CONCLUSIONS: SW improved longitudinal growth, lipid profile, and trunk and lean fat in Tx patients. In prepubertal recipients, the decrease in TyG suggests better IS.

Assessing the clinical utility of quantitative computed tomography with a routinely used diagnostic computed tomography scanner in a cancer center.

The purpose of this study was to characterize quantitative computed tomography (QCT) in our multi-detector computed tomography (MDCT) scanner with regard to the influence of the QCT phantom on dose and the influence of varying mA and CIRS phantom size on bone mineral density (BMD) measurements. We accomplish this by scanning a commercially available QCT phantom and a corresponding quality assurance phantom. To assess the feasibility of having the QCT phantom in place while patients are being scanned, we measured radiation dose difference in a CT body phantom with and without the QCT phantom on the CT table and also, with and without the use of dose modulation programs. We also analyzed reconstructed QCT phantom images with the manufacturer's software to measure BMD. Although patient characteristics may be different, leading to different mA values, the influence of the QCT phantom on the dose to patients was minimal when compared with doses measured without the phantom in place. Average BMD measurements were not significantly affected by varying mA, for a fixed-size phantom. The average BMD exhibited a weak dependence on computerized imaging reference systems (CIRS) torso phantom size, with a propensity for decreasing BMD with increasing size. Measurement precision was unaffected by varying CIRS size. Having the ability to measure bone density as part of the routine management of cancer patients, with no added cost, time, or radiation dose, will allow for the prospective evaluation of bone mineral changes. We believe that this ability will facilitate the detection of abnormal bone loss and will lead to better management of this loss and, thus, reduce the complications and associated morbidity in these cancer survivors.